Abrasive finishing elements, tools made from such elements, and methods of making such tools

Abstract

A plastic strip or strap having granular abrasive embedded homogeneously throughout is cut, shaped and formed into a variety of abrasive finishing tools. The plastic working element is preferably rather stiff 6/12 nylon and contains about 30 to 45% by weight of abrasive material. The strip or strap is formed by extrusion of such non-elastomeric plastic through a ceramic die opening and as extruded has an indefinite length in the machine direction, a controlled uniform thickness, and a width which is approximately 5 to 50 times or more the thickness. A preferred width to thickness ratio is about 30:1, or about 1 mm to 3 cm. The strip or strap may be cut to the desired length and partially embossed, serrated or scored either lengthwise or transversely to provide fracture or flex lines. The spacing of the serrations or score lines controls the degree of flexibility or aggressiveness of the tool working face. The use of a fairly wide strip with serrations or scores not only provides an improved tool but greatly facilitates the construction of the tool. The invention includes a variety of tools formed from the abrasive strip or strap and these include radial or flap wheels, both serrated and non-serrated, internal tools using a rotatable stem, also both serrated and non-serrated. Such tools may employ the strips or straps straight, or bent to an S-shape or formed so that the edge of the strip or straps is in the form of a helix. Such strips may be secured to the stem at a notch to provide both a side and bottom working edge for internal wall work. Also the edges of the strip may be chamfered. A spot facing tool may be formed by tightly coiling a length of strip or strap and then driving the coiled strip into liquid adhesive at the bottom of a holder. The strips or straps may be folded around wires or cores and clinched with a channel to form a strip which may then be assembled to form disc or cylindrical strip tools. In such construction the strip or strap may be scored or serrated transversely of its length.

What is claimed is: 
     
       1. A working element for abrading tools comprising a strip consisting of a substantially rigid non-elastomeric synthetic plastic material, having a length, width and thickness and containing abrasive material embedded therein homogeneously throughout wherein said strip is scored. 
     
     
       2. A working element as set forth in claim 1 wherein said plastic material is nylon. 
     
     
       3. A working element as set forth in claim 1 wherein said strip contains about 30-45% by weight of granular abrasive material. 
     
     
       4. A working element as set forth in claim 1 wherein said strip has a width at least 5 times its thickness. 
     
     
       5. A working element as set forth in claim 1 wherein said strip has a width at least 10 times its thickness. 
     
     
       6. A working element as set forth in claim 1 wherein said plastic material is 6/12 nylon. 
     
     
       7. A working element as set forth in claim 1 wherein said plastic material is aramid. 
     
     
       8. A working element as set forth in claim 1 wherein said plastic material is polyester. 
     
     
       9. A working element as set forth in claim 1 wherein said plastic material is a polyimide. 
     
     
       10. A working element as set forth in claim 1 wherein said strip has a width to thickness ratio of about 30 to 1. 
     
     
       11. A working element as set forth in claim 1 wherein said strip has a thickness of about one millimeter. 
     
     
       12. A working element as set forth in claim 1 wherein said strip has a major parallel longitudinally and transversely extending faces defined by the length and width of the tape, respectively, said faces including said scoring. 
     
     
       13. A working element as set forth in claim 12 wherein said scoring extends longitudinally of said strip. 
     
     
       14. A working element as set forth in claim 12 wherein said scoring extends transversely of said strip. 
     
     
       15. A working element as set forth in claim 12 wherein said scoring extends partially longitudinally or transversely of said strip. 
     
     
       16. A working element as set forth in claim 12 wherein said scoring includes parallel score lines in said major faces. 
     
     
       17. A working element as set forth in claim 16 wherein said score lines in the respective faces are opposite each other whereby the thickness of the strip is substantially reduced between the opposite score lines. 
     
     
       18. A working element as set forth in claim 17 wherein said score lines enhance the flexibility of said strip and the closer said score lines are spaced, the greater the flexibility. 
     
     
       19. A working element as set forth in claim 16 wherein each score line is a rounded indentation. 
     
     
       20. A working element as set forth in claim 16 wherein each score line is a V-shape indentation. 
     
     
       21. A working element as set forth in claim 16 wherein each score line is shaped to promote controlled fracture of said strip along said score line when the tool in which said element is used is in operation. 
     
     
       22. A working element as set forth in claim 1 wherein said scoring forms partial slits in said strip is partially slit. 
     
     
       23. A working element as set forth in claim 22 wherein said strip includes parallel closely spaced slits. 
     
     
       24. A working element as set forth in claim 23 wherein said slits extend each to the same extent from one or both edges transversely of the strip. 
     
     
       25. A working element as set forth in claim 23 wherein said slits extend each to the same extent longitudinally of the strip. 
     
     
       26. An abrasive element for an abrasive tool comprising a strip of abrasive containing rigid non-elastomeric synthetic plastic having a length, width and thickness, folded longitudinally and clinched at the fold by a U-shape channel support so that the lateral edges of the strip are generally adjacent and parallel to each other. 
     
     
       27. A strip as set forth in claim 26 wherein said plastic is nylon. 
     
     
       28. A strip as set forth in claim 26 wherein said strip contains about 30-45% by weight of granular abrasive material. 
     
     
       29. A strip as set forth in claim 26 wherein said strip has a width at least 10 times its thickness. 
     
     
       30. A strip as set forth in claim 26 wherein said plastic material is selected from a group consisting of 6/12 nylon, aramids, polyesters, and polyimides. 
     
     
       31. A strip as set forth in claim 26 wherein each strip includes a plurality of folded and clinched tapes. 
     
     
       32. A strip as set forth in claim 26 wherein each tape is provided with slits extending transversely of the strip from each outer lateral edge. 
     
     
       33. A strip as set forth in claim 26 wherein each strip is provided with scoring extending transversely of the tape from each outer edge. 
     
     
       34. A strip as set forth in claim 33 wherein the configuration of the scoring promotes controlled fracture of the strip when the tool is in use. 
     
     
       35. A strip as set forth in claim 26 wherein said strip is folded longitudinally about an interior core plastic mono filament. 
     
     
       36. A working element for abrading tools comprising a substantially rigid non-elastomeric plastic strip having a length, width and thickness, and containing abrasive material embedded therein homogeneously throughout, and wherein said strip is heated and shaped or folded. 
     
     
       37. A working element as set forth in claim 36 wherein said strip includes score lines. 
     
     
       38. A working element as set forth in claim 37 wherein each score line is shaped to promote fracture of said strip along said score line when the tool in which said element is used is in operation. 
     
     
       39. A working element for abrading tools comprising a substantially rigid non-elastomeric plastic strip having a length, width and thickness, and containing abrasive material embedded therein homogeneously throughout, and wherein said strip is heated and shaped or folded, and, when cooled, substantially retains its shaped or folded condition.